Apple Tests M3 Ultra Chip in New MacBook Pro Models, User Discovers Clue in iOS 18 Internal Build

Apple’s latest 14-inch and 16-inch MacBook Pro models feature the highly capable M4 Max as the top-tier option, while the exceptionally powerful M3 Ultra is designated exclusively for the Mac Studio. Early indications suggested that thermal limitations might hinder Apple from incorporating an ‘Ultra’ class chipset in their portable models. However, there have been whispers suggesting that Apple was experimenting with integrating this high-end chipset into their laptop range, evident from references uncovered in the iOS 18 framework.

Evidence of M3 Ultra Testing on MacBook Pro Models Discovered in iOS 18

A revealing post on Bilibili, brought to light by MacRumors, unveiled internal code from an iOS 18 build running on an iPhone 16 prototype. This code hinted at testing of the M3 Ultra on Apple’s 14-inch and 16-inch MacBook Pro models. The specific identifiers for these machines, known as J514d and J516d, were found nestled within the ‘/AppleInternal/Diags/Tests/’ folder of the software.

For those closely observing Apple’s naming conventions, the existing MacBook Pro models with M3 Pro and M3 Max chips are labeled as J514 and J516. The addition of the letter ‘d’ suggests these are experimental variants specifically coupled with the M3 Ultra chipset; this aligns with the Mac Studio, which has a similar identifier—J575d. This evidence fuels speculation that, under the right circumstances, the M3 Ultra could have been the powerhouse behind a new line of MacBook Pro models.

For context, the M3 Ultra represents Apple’s most advanced custom silicon to date, boasting a remarkable configuration that includes up to a 32-core CPU, 80-core GPU, and a staggering 512GB of unified RAM. The thermal constraints likely played a critical role in Apple’s decision not to include this formidable hardware in the MacBook Pro lineup. Given that the M3 Ultra features a larger die compared to the M3 Max or M4 Max, accommodating this chip would necessitate a redesign of the motherboard. This change would also require increasing the chassis thickness to fit the enhanced cooling system needed for optimal performance.

Moreover, integrating the M3 Ultra into the MacBook Pro lineup could have potential repercussions for sales of the Mac Studio and the anticipated Mac Pro, leading to concerns about market cannibalization. As it stands, it appears that the forthcoming portable models will comfortably feature the M5 Max, expected to launch later this year, keeping a clear distinction between Apple’s professional desktop and laptop offerings.

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